Production of artificial materials



Patented July 6, 1937 PRODUCTION OF ARTIFICIAL MATERIALS William Alexander Dickie and Percy Frederick Combe Sowter, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application March 24, 1932, Serial No. 601,043. In Great Britain May 12, 1931 10 Claims.

This invention relates to the manufacture of artificial filaments, threads, ribbons, films and other products by wet spinning processes from solutions of organic derivatives of cellulose, for

5 example cellulose acetate, formate, propionate or butyrate, or methyl, ethyl or benzyl cellulose, and is a continuation in part of U. S. application S. No. 402,785 filed 26th October, 1929.

U. S. application S. No. 402,785 describes processes wherein materials of the above type are produced by wet spinning processes in which coagulation is effected in the presence of relatively strong solvents or swelling agents for the cellulose derivative, or in which solvents which are less volatile than the non-solvent medium of the coagulating bath are incorporated in the spinning solution itself wholly or in part in place of the solvents in the coagulating bath. The solvent or swelling agent may be present in such proportions that the materials emerge from the coagulating medium in a relatively plastic condition.

The said application describes a further modification in which the materials are subjected to the action of relatively strong solvents or swelling agents immediately after coagulation.

We have now discovered that excellent results may be obtained by employing as solvents or swelling agents in wet spinning processes such as those to which the invention of U. S. application S. No. 402,785 relates, organic derivatives of polyhydric alcohols and in particular esters or ether-esters thereof.

Among such derivatives mention may be made of glycol mono-acetate, glycol diacetate, methyl glycol mono-acetate and other esters, especially mono-carboxylic esters, of glycol and its alkyl substitution products. Thus, for example, by spinning solutions of cellulose acetate in acetone into aqueous spinning baths containing about 38-40% of methyl glycol mono-acetate, lustrous filaments of soft feel and relatively high tenacity may be obtained. Good results are obtained in the case of glycol mono-acetate when the aqueous coagulating medium contains from 45-60% of the solvent. Similarly with glycol diacetate good results are obtainable with aqueous solutions of 50-70% concentration. These proportions are given merely in illustration of the invention and are not intended to be in any way limitative. The proportion of the particular solvent employed will naturally depend upon the nature of the solvent and upon such other factors as the composition of the spinning solution and of the non-solvent coagulating medium;

The esters of the invention may be contained wholly or'in part in the coagulating medium, in the spinning solution, or in a treating agent applied to the coagulated materials continuously with their production.

In making up the spinning solution any suitable solvent, simple or mixed, may be employed. Among such solvents we may instance acetone, acetic acid, formic acid, and mixtures of relatively non-polar liquids such as ethylene and methylene dichlorides with polar liquids such .as ethyl and methyl alcohol. We prefer to employ acetone as the solvent. The spinning solution may contain, apart from latent solvents such as the alcohols and halogenated hydrocarbons specified above, other non-solvents for the cellulose derivative, for example mineral oils and other liquid hydrocarbons, and olive oil, castor oil or other oils of natural origin. The spinning solusolvents be present in a proportion sufficient to 1 precipitate the cellulose derivative from solution. The proportions may however be such that the cellulose derivative is near the precipitation point. Where a solvent compatible with water is employed, such for example as acetone, the spinning solution may with advantage contain a proportion of water determined in accordance with the solubility characteristics of the particular cellulose derivative. Apart from the solvents of the invention which may or may not be con-, tained in the spinning solution itself, there may be present in said solution other relatively high boiling solvents for the cellulose derivative, for example any of those referred to below asoptional constituents'of the coagulating medium. Spinning may be effected so that at least a part of any high boiling solvents ,or non-solvents present in the spinning solution are retained in the materials. The spinning solution may contain solid or liquid substances in dispersed or finely divided form. Thus, finely divided solid substances may be introduced into the spinning solution so as for example to modify the lustre of the resulting products, see U. S. applications S. Nos. 444,622 filed 15th April, 1930, 464,122 filed 16th June, 1930, 473,781 filed 7th August, 1930 now Patent No. 2,039,302 and 473,782 filed 7th August, 1930 now Patent No. 2,039,303.

The percentage of cellulose derivative contained in the spinning solution will naturally depend to some extent upon the nature of the solvent medium, and upon the particular results desired, for example the denier of the materials to be produced. Good results are obtained with spinning solutions containing from 15-35% of the cellulose derivative. When relatively high percentages of cellulose derivative are employed, spinning may be facilitated by reducing the viscosity of the solution by suitable means, for example by the addition to the solution of electrolytes or the like, as described in U. S. application S. No. 401,625 filed 22nd October, 1929, or by spinning at a temperature above atmospheric, see U. S. application S. No. 316,617 filed 1st November, 1928 now Patent No. 1,997,632.

Any suitable non-solvent for the cellulose derivative may be present in the coagulating medium. We'prefer to employ water as the non-solvent, but suitable non-aqueous non-solvents for the cellulose derivative may be employed. Thus, for example, toluene, any of the three xylenes, ligroin, kerosene, or other aliphatic or aromatic hydrocarbons of relatively high boiling point, alcohols which are non-solvents for the cellulose derivative, employed alone or in admixture, may consti' tute or be contained in the coagulating medium. The non-solvent must of course be capable of dissolving at least one constituent present in substantial proportions in the spinning solution. The coagulating medium may contain any desired relatively non-volatile solvents, swelling agents or plasticizers for the cellulose derivative, for example triacetin, diacetone alcohol, ethyl lactate, ethyl tartrate, diethyl phthalate and tricresyl phosphate. Although it is preferable that any solvent present in the coagulating medium should be of relatively low volatility, the presence of volatile solvents is not excluded. The coagulating medium may also contain substances, for example salts, sugars and the like, capable of diminishing the solubility of any solvent present in the nonsolvent coagulating agent, according to the principle disclosed in U. S. application S. No. 469,622 filed 21st July, 1930.

Where the polyhydric alcohol derivative. is present in a treating medium, applied to the coagulated materials as an after-treatment, such treating medium may contain constituentsof the various types referred to above in connection with the coagulating medium. The action of the said derivative may, for example, be tempered by the presence of suitable diluents, or assisted by the presence of other solvents, swelling agents or plasticizers for the cellulose derivative.

Any solvents retained in the filaments or materials after emergence from the coagulating medium may if desired be removed from the materials by any suitable means, for example by washing with water or other suitable agent, or by passing the materials through a heated atmosphere or over a heated surface. In removing such agents by a washing process, it is preferable to employ a series of wash liquids containing decreasing quantities of the agent to be removed. It is not, however, necessary to remove the glycol derivatives completely. In fact, the feel and appearance of the materials may be improved by allowing a certain proportion of the solvent to remain therein. This proportion should not, however, be so great as to decrease the strength of the filaments substantially. The retention of a certain proportion of the solvent may have an important efiect upon the behaviour of the materials towards delustring agents. Thus materials containing the glycol derivatives of the invention are found to be in general more readily delustrable by the action oi hot or boiling aqueous media than are similar materials which do not contain relatively nonvolatile solvents. On the other hand, by subjecting materials containing the solvents of the invention to the action of substantially dry steam, for example by the process of British Patent No. 332,187, the materials may be rendered more resistant to delustring than similar materials free from solvent.

A stretch may be imparted to the materials during the course of their manufacture according to the process of the invention. Any suitable means may be employed for producing this effect, for example the materials may be passed in contact with two or a series of rotating members of successively increasing peripheral speeds; or the stretch may be imparted by any swift, bobbin, spinning pot, or other collecting device, run at a suitable speed, or the principles of U. S. applications S. Nos. 585,379 filed 7th January, 1932 now Patent No. 2,027,419 and 593,859 filed Feb. 18, 1932, now Patent No. 2,054,852 corresponding to British application No. 9427 31 filed 27th March, 1931 may be applied.

Theprocesses of the invention may be combined with any other suitable treating processes designed, for example to modify the colour, lustre, feel, strength or other properties of the material.

Fatty or oily bodies may be applied to the materials at any stage in their manufacture. Such substances may be adapted to facilitate subsequent mechanical operations such as weaving or knitting, or may be particularly adapted to impart a soft feel to the materials. Such oily or fatty bodies may, for example, be presentin the coagulating and/or after-treatment media. They may, according to theirsolubility or otherwise in these media, be present in solution, in the form of a dispersion, or even as a separate layer. Thus when aqueous coagulating or treating media are employed, water soluble oily or fatty bodies, for example Turkey red oil, and other sulphonated oils of organic or mineral origin may be contained in solution in such baths. On the other hand, insoluble oils and the like may be dispersed throughout the bath, or may float as a layer on the surface thereof.

The following examples illustrate the invention, but they are not to be considered as limiting it in any way:--

Example 1 A 20% solution of cellulose acetate in acetone is extruded through spinning jets having 104 orifices of .07 mm. diameter into a coagulating bath consisting of an aqueous solution of methyl glycol acetate of a concentration of 39% by weight. The length of filaments immersed in the bath is about 10" and there is an air run of about 50" after. emergence to the spinning bath. The filaments are drawn off at a rate of 50 metres per minute. A thread, of denier, may thus be obtained, having a high-tenacity.

. Example 2 1 A 20% solution of cellulose acetate in acetone is spun as in Example 1, using as coagulating bath a 45% aqueous solution of glycol mono acetate. The phrase continuously with their production where employed in the following claims is to be understood to include, where the context permits, both treatments eifected in the coagulating bath, and also treatments effected in subsequent baths before the materials are collected and dried.

What we claim and desire to secure by Letters Patent is:

1. In a process for the manufacture of articial filaments, threads, ribbons, films and the like from a solution of an organic derivative of cellulose by extrusion into a coagulating medium, the step of treating the extruded materials, continuously with their production, with a liquid medium containing an esterified polyhydric alcohol in a concentration of between 38 and 70%.

2. In a process for the manufacture of artificial filaments, threads, ribbons, films and the like from a solution of an organic derivative of cellulose by extrusion into a coagulating medium, the step of treating the extruded materials, continuously with their production, with a liquid medium containing, in a concentration of between 38 and 70%, an esterified polyhydric alcohol, which esterified polyhydric alcohol contains an ether group.

3. Process for the manufacture of artificial filaments or threads, which comprises extruding a solution containing an organic derivative of cellulose into an aqueous coagulating medium containing an esterified polyhydric alcohol in a concentration between 38 and 70%.

4. Process for the manufacture of artificial filaments or threads, which comprises extruding a solution containing an organic derivative of cellulose into an aqueous coagulating medium containing, in a concentration between 38 and 70%, an esterified polyhydric alcohol, which esterified polyhydric alcohol contains an ether group.

5. In a process for the manufacture of artificial filaments or threads from a solution of cellulose acetate by extrusion into an aqueous coagulating medium, the step of treating the extruded materials, continuously with their production, with a liquid medium containing an esterified polyhydric. alcohol in a concentration between 38 and 70%. v

6. Process for the manufacture of artificial filaments or threads, which comprises extruding a solution containing cellulose acetate into an aqueous coagulating medium containing an esterified polyhydric alcohol in a concentration between 38 and 70%.

7. Process for the manufacture of artificial filaments, threads, ribbons, films and the like which comprises extruding solutions of cellulose acetate into an aqueous coagulating medium containing the mono-acetate of glycol in about concentration.

8. Process for the manufacture of artificial filaments, threads, ribbons, films and the like, which comprises extruding a solution containing cellulose acetate into an aqueous coagulating medium containing methyl glycol mono-acetate in a concentration of between 38 and 9. Process for the manufacture of artificial filaments, threads, ribbons, films and the like, which comprises extruding a solution containing cellulose acetate into an aqueous coagulating medium containing ethyl glycol monoacetate in a concentration of between 38 and 70%. I

10. Process for the manufacture of artificia filaments or threads, which comprises extruding a solution containing cellulose acetate into an aqueous coagulating medium containing glycol mono-acetate in a concentration between 38 and 70%.

WILLIAM ALEXANDER DICKIE. PERCY FREDERICK COMBE SOWTER. 

